1. Field of the Invention
A fusible device for programmable thick film networks used in attenuators, voltage dividers and similar circuits made by sandwiching a narrow thick film metal strip between two layers of dielectric glaze or glass. This energy sensing device has a low initial resistance and a very high open circuit resistance.
2. Description of the Prior Art
Fusible devices are well known in the prior art, their exact construction being a function of their application or use in a circuit. In many cases it is desirable to use thick film fusible devices for setting levels of attenuation in attenuators or fine tuning in voltage dividers. However, prior art devices have had several drawbacks. Some have had too low a resistance. Others have had restrictions on materials. Still others have been of a thin film type.
A typical example of a presision electric fuse is disclosed in U.S. Pat. No. 3,401,452. This patent discloses a composite metal-glass fuse element having an electrically-conductive fuse metal extending between and electrically connecting spaced-apart fuse electrodes, and a layer of electrically insulating glass covering the metal layer in intimate contact therewith for quenching the fuse metal after it has been blown by a current overload, whereby arcs which tend to develop across the blown metal are effectively suppressed. The object of this patented device was to provide a precision miniature electrical fuse which produces a fast and decisive break at the rated breaking current. The fuse will remain intact through long periods of operation and only ruptures in the event of an overload. In contrast, the fuse of the present invention is intended to be intentionally blown for the purpose of programming a circuit. While similar in construction to this prior art patent, the fuse of the present invention differs in several notable respects.